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Classical dyskeratosis congenita (DC) is a multisystem disorder characterized by the mucocutaneous triad of abnormal skin pigmentation, nail dystrophy and mucosal leucoplakia. The prevalence was estimated to 1 in 1,000,000. DC exhibits considerable clinical and genetic heterogeneity. Clinical manifestations in DC often appear during childhood although there is a wide age range. A variety of other abnormalities have been reported (dental, gastrointestinal, genitourinary, hair greying/loss, immunological, neurological, ophthalmic, pulmonary and skeletal). Bone marrow (BM) failure is the principal cause of early mortality with an additional predisposition to malignancy and fatal pulmonary complications. X-linked recessive, autosomal dominant and autosomal recessive forms are recognised. The genes (DKC1 and TERC) mutated in two subtypes of DC both encode components of the telomerase complex and DC is now believed to be principally due to defective telomerase function. The identification of DKC1 mutations in patients with Hoyeraal-Hreidarsson (HH) and of TERC mutations in some patients with aplastic anaemia (AA) and myelodysplasia (MDS) have extended the range of patients who can be regarded as having DC. In families where mutation in the DKC1 or TERC gene has been characterized antenatal diagnosis is possible. From a clinical perspective the link between DC and AA and in turn to defective telomerase suggests that treatments directed at correction of telomerase activity might benefit DC/AA patients who do not respond to conventional therapy. At present haemopoietic stem cell transplantation (SCT) using low intensity protocols represents the only curative option for DC patients developing BM failure. |